Switching isolators



Se t. 22, 1970 SWITCHING ISOLATORS Filed Sept. 30, 1968 w. J; JOYCE 3,530,263

United States Patent M US. Cl. 200-48 10 Claims ABSTRACT OF THE DISCLOSURE A switch isolator has two support insulators 2, 3 each carrying a fixed isolator contact 17, 18 in series with a series-connected pair of circuit interrupters (9 to 12), and a rotatable centre post 4 which carries a conductor blade 5 for bridging the two fixed isolator contacts 17, 18. A drive mechanism 7, 8 is provided for slowly rotating the post 4 and thus the blade 5, and a separate operating mechanism 19 is provided for rapidly opening the circuit interrupters (9 to 12) through suitable linkage. The operating mechanism 19 for the circuit interrupters (9 to 12) is preferably in the form of a stored energy device utilising compressed air, hydraulic fluid or mechanical springs.

This invention relates to switch isolators of the kind having a conductor blade mounted on a rotatable support post so as to rotate with the support post, a pair of support insulators spaced from each other and from the support post and each carrying a fixed isolator contact, and operating means for rotating the support post between one position in which the conductor blade bridges the two fixed isolator contacts and another posi tion in which the conductor blade is spaced from each fixed isolator contact by a distance suitable for isolation.

Switch isolators of the kind described intended for use in the low, medium or high voltage ranges have been provided with load breaking heads or arc chutes, the fault making capacity being provided by the conductor blade. Such switch isolators have auxiliary arcing contacts which are shorted by the conductor blade when it is in its closed position and which are tripped by the conductor blade so as to open after the conductor blade.

For the extra high voltage range the length and mass of the conductor blade is such as to make it unsuitable for use as a fault making device in atmospheric air and generally its speed of movement is too slow for it to be suitable for use as the means of tripping auxiliary contacts such as flicker blades or overtoggle spring devices and thus provide the desirable speed of operation of the auxiliary contacts. Furthermore it is difiicult to arrange for the conductor blade to provide the short time closing operation required in conjunction with synchronising.

According to this invention, we provide a switch isolator of the kind described wherein a circuit interrupter is carried by one of the support insulators and is connected to a corresponding fixed isolator contact so as to be connected in series with the conductor blade when the conductor blade bridges the fixed isolator contacts, and further operating means are provided for operating the circuit interrupter.

Preferably each support insulator carries a series-connected pair of said circuit interrupters, said further operating means being provided for operating all said circuit interrupters.

Conveniently the operating means for rotating the support post and said further operating means are housed within dilferent housings.

Patented Sept. 22, 1970 The said further operating mechanism for the or each circuit interrupter is preferably in the form of a stored energy device utilising, for example, compressed air, hydraulic fluid, or mechanical springs, and is arranged so as to provide for rapid movement of the interrupter contacts.

In order that the invention may be readily understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawing which is a diagrammatic elevation of the switch isolator.

Referring to the drawing, the switch isolator includes a base frame 1 which carries two spaced vertical support insulators 2 and 3, and a vertical support post 4 which is positioned centrally between said insulators. The post 4 carries a conductor blade 5 at its upper end and is rotatably mounted on the base frame 1 via a shaft 6 which is coupled to a drive mechanism contained within a housing 7 via gearing 8 for controlling the speed and direction of rotation for said post. This mechanism may be of any suitable form, for example, a hydraulic motor and pump arrangement, for rotating the centre post 4 slowly in the required rotational direction.

In this embodiment, the upper end of each support insulator 2, 3, carries a pair of circuit interrupters 9, 10, and 11, 12 respectively. Each pair of interrupters is mounted in an L-shaped, series-connected formation on a support casing 13 which in turn is mounted on top of its respective support insulator 2 or 3. A voltage sharing capacitor 14 is provided for each interrupter. The outer interrupters 9 and 12 of the pairs which ex tend on the side of the respective support insulator 2, 3 remote from the post 4 are each provided with a terminal 15, 16 respectively for connection to an external circuit, whilst the inner interrupters 10 and 11 of the pairs which extend beyond the end of the respective support insulator 2, 3 adjacent to the longitudinal axis thereof are provided with fixed isolator contacts 17, 18 respectively for the conductor blade 5.

The interrupter operating mechanism is contained within a housing 19 and comprises a stored energy device utilising compressed air and is connected to the movable contact of each interrupter via rods and links (not shown). The rods extend from the housing 19 to the interrupters via the support insulators 2, 3, and those rods which are within the insulators are of electrically insulating material. The rods are preferably arranged in pairs so that one rod may act in tension for closing the movable contacts, and the other rod may also act in tension for opening said contacts.

An earth switch 20 in the form of a pivoted blade is associated with each support insulator 2, 3 and extends from the base frame 1, which is positively maintained at earth potential, to its respective outer terminal 15 and 16. The operating mechanism for the earth switch is not shown in the drawing but would normally comprise a handwheel, gearing and safety interlock device for each earth switch so that each earth switch can be used independently.

In operation of the switch isolator, assuming that the circuit interrupters 9 to 12 are closed, and the conductor blade is in a closed position bridging the fixed contacts 17 and 18, the interrupter operating mechanism is first energized to open the interrupter contacts rapidly and, after a time interval sufiicient for the arcs drawn by the interrupters to be extinguished, the isolator mechanism is operated to rotate the conductor blade 5 slowly to its open position.

When reclosing the isolator, the conductor blade 5 is first moved to its closed position and the interrupter operating mechanism is then activated to close the interrupter contacts. This latter operation may be carried out automatically. However, where the interrupters are required to be closed only when the external supplies are in synchronism said latter operation is preferably carried out manually, or by a synchronising relay. The interrupters and their operating mechanism are arranged such that, when the interrupters are in their closed positions, there is no inherent force tending to cause the interrupter contacts to move to their open positions.

The drive mechanism for the central post 4 and the operating mechanism for the interrupters may be interlocked for sequential operation.

The circuit interrupters incorporated in the arrangement may be of any suitable form and may, for example, be of the form described in British patent application No. 44,240/ 67, and the corresponding U.S. patent application Ser. No. 763,589, filed Sept. 30, 1968.

It will be appreciated that with the arrangement described above the interrupters may be used to close the external circuit after an earth switch has been connected to its respective terminal. In this way the arrangement provides the same facilities as would be provided by a circuit breaker.

It will also be appreciated that the arrangement described is for use with a single phase circuit. If the invention is to be used for a three phase circuit, then three switch isolators constructed in accordance with the invention would be required. One operating mechanism of each type would normally be used for the three phases and would be coupled together by mechanical linkage, vis. one for blades, one for interrupters and one for earth switches.

It will be appreciated that the operating mechanism for the interrupters may utilise hydraulic fluid or mechanical springs instead of compressed air as described. Where the mechanism is similar to the drive mechanism for the centre post, e.g. where they are both hydraulic, they may conveniently be contained within a common housing.

It is not essential to provide two earth switches 20 as described; a single earth switch 20 associated with one of the support insulators 2 or 3 may be provided if required.

I claim:

1. A switch isolator having a conductor blade rigidly mounted on a rotatable support post; a pair of support insulators spaced from each other and from the support post; a spaced apart pair of fixed isolator contacts, each fixed isolator contact being carried by a corresponding support insulator; and operating means for rotating the support post between one position in which the conductor blade bridges the spaced apart pair of fixed isolator contacts and another position in which the conductor blade is spaced from each fixed isolator contact by a distance suitable for isolation; wherein the improvement comprises:

(i) a circuit interrupter carried by one of the support insulators and connected to the corresponding fixed isolator contact so as to be connected in series with the conductor blade when the support post is in said one position; and

(ii) further operating means for operating the circuit interrupter and capable of being actuated independently of the first-mentioned operating means.

2. A switch isolator according to claim 1, wherein the improvement further comprises two series-connected pairs of said circuit interrupters, each series-connected pair of said circuit interrupters being carried by a corresponding support insulator, said further operating means being provided for operating all said interrupters.

3. A switch isolator according to claim 2, wherein the improvement further comprises a said series-connected pair of said circuit interrupters being mounted in an L-shaped formation, one of said series-connected pair of said circuit interrupters which affords one arm of the L extending on the side of the respective support insulator remote from the support post and carrying corresponding terminal, and the other of said series-connected pair of said circuit interrupters which affords the other arm of the L extending beyond the end of the respective support insulator adjacent to the longitudinal axis thereof and carrying the corresponding fixed isolator contact.

4. A switch isolator according to claim 3, wherein the improvement further comprises an earth switch associated with a respective support insulator and operable to connect said circuit interrupter which affords said one arm of the respective L to a base frame which carries said support post and said support insulators and which is positively connected to earth potential.

5. A switch isolator according to claim 1, wherein the improvement further comprises said operating means for rotating the support post and said further operating means being housed within separate housings.

6. A switch isolator according to claim 5, wherein the improvement further comprises said operating means for rotating the support post comprising a hydraulic motor and pump arrangement and said further operating means being in the form of a stored energy device utilising compressed air.

7. A switch isolator according to claim 1, wherein the improvement further comprises said further operating means being capable of being arranged to automatically close the contacts of said circuit interrupter once the support post has reached said one position.

8. A switch isolator according to claim 1, wherein the improvement further comprises manually operable means provided for actuating said further operating means so as to close the contacts of said circuit interrupter.

9. A switch isolator according to claim 1, wherein the improvement further comprises a synchronising mechanism which is arranged to actuate said further operating means so as to close the contacts of said circuit inter- References Cited UNITED STATES PATENTS 7/1945 Strang.

FOREIGN PATENTS 856,014 11/1952 Germany.

ROBERT K. SCHAEFER, Primary Examiner H. I. HOHAUSER, Assistant Examiner US. Cl. X.R. 200-448 

18. AND DRIVE MECHANISM 7, 8 IS PROVIDED FOR SLOWLY ROTATING THE POST 4 AND THUS THE BLADE 5, AND A SEPARATE OPERATING MECHANISM 19 IS PROVIDED FOR RAPIDLY OPENING THE CIRCUIT INTERRUPTERS (9 TO 12) THROUGH SUITABLE LINKAGE. THE OPERATING MECHANISM 19 FOR THE CIRCUIT INTERRUPTERS (9 TO 12) IS PREFERABLY IN THE FORM OF A STORED ENERGY DEVICE UTILISING COMPRESSED AIR, HYDRAULIC FLUID OR MECHANICAL SPRINGS. 